3-indoleacetohydroxamic acids

ABSTRACT

2-METHYL-5-METHOXY-3-INDOLEACETOHYDROXAMIC ACID COMPOUNDS OF THE FORMULA:   WHEREIN R is a member selected from the group consisting of hydrogen, phenylmethyl, allyl, vinyl, isopropenyl, benzoyl, chlorobenzoyl, methoxybenzoyl, and thiomethylbenzoyl, and process for preparing same. These compounds exhibit excellent antiinflammatory, antipyretic and analgesic effects.

United States Patent Franco De Martlis Inventors Turin; Eduardo Arrigoni-Martelli, Milan; Teresio Tamietto, Turin, all of Italy Appl. No. 822,320 Filed May 6, 1969 Patented Nov. 30, 1971 Assignee lnstituto Biologico Chemioterapico ABC" S.p.A. Turin, Italy Priority May 2], 1968 Italy 5 1749 A/68 S-INDOLEACETOHYDROXAMIC ACIDS 5 Claims, No Drawings [1.8. CI ..26 0/326.13A 260/326. 1 3 R, 424/274 Int. Cl C07d 27/56 Field of Search ..260/326. l 3, 326.13 A

CLAIM: 2-methyl-5-methoxy-3-indoleacetohydroxamic acid EQ P 9 e Law ess CHzCONHOH wherein R is a member selected from the group consisting of hydrogen, phenylmethyl, allyl, vinyl, isopropenyl, benzoyl, chlorobenzoyl, methoxybenzoyl, and thiomethylbenzoyl, and process for preparing same. These compounds exhibit excellent anti-inflammatory, antipyretic and analgesic effects S-INDOLEACETOI'IYDROXAMIC ACIDS SUMMARY OF THE INVENTION This invention relates to derivatives of the 2-methyl-5- methoxy-3-indole-acetohydroxamic acid of the general formula omooNnon wherein R stands for a hydrogen atom, an aryl-alkyl group, an alkene or an aroyl group. Phenylmethyl is preferred among aryl-alkyls. Typical representatives of the alkene substituent are allyl, vinyl and isopropenyl, allyl being preferred. The aroyl group may be benzoyl, chlorobenzoyl, methoxybenzoyl, thiomethylbenzoyl or, preferably, p-chlorobenzoyl.

The above-mentioned compounds result to be effective as anti-inflammatory agents on the following tests: edemas from carrageenan, edemas from formalin, and polyvinyl-pyrrolidone sponge granuloma. They are moreover active as antipyretic and analgesic agents and are characterized by low acute toxicity, their therapeutical index being therefore particularly favorable.

DETAILED DESCRIPTION OF THE INVENTION The compounds may be prepared by reacting esters of lower aliphatic alcohols (one to four carbon atoms) of 2- methyl-5-methoxy-3-indoleacetic acid R-substituted at position 1 (wherein R is as defined hereinbefore) with hydroxylamine in anhydrous methanol at elevated temperature according to reaction 11, or by reacting at room temperature a chloride of the said acid with hydroxylamine in a lower alcohol or water, according to reaction III:

(III) EXAMPLEI Part lPreparation of 1-allyl-2-methyl-5-methoxy-3-indoleacetic acid methyl ester:

CHg-COOCHB CHaO- 0.04 Moles sodium hydride (NaI-I in 20 percent Merck dispersion) are vigorously stirred during 1 hour. while protected against moisture with 20 ml. freshly distilled dimethylformamide (DMF) and subsequently slowly admixed while stirring with 0.0399 moles of 2-methyl-5-methoxy-3-indoleacetic acid methyl ester dissolved in 24 ml. DMF while externally cooling by means of an ice bath. Stirring and cooling are continued during about 1 hour until hydrogen gas has fully evolved. A solution is 20 ml. DMF of 0.0415 moles allyl chloride is dropped through a dropping funnel and allowed to react during 1 hour while further stirring and cooling. The container is sealed and placed into a refrigerator during at least 48 hours.

On expiration .of this period the reaction mass is poured in 400 ml. cold water, stirred and allowed to stand a few hours in a refrigerator: a precipitate is formed consisting of unctuous lumps, which are recovered by filtering, lavishly washed on the filter with water, dried in vacuum over CaCl and thoroughly repeatedly washed with ligroin (b.p. 4070 C.

The brown-colored solid lumpy mass is purified by consecutively crystallizing from hot aqueous ethyl alcohol, 5.750 g. of lallyl-2-methyl-5-methoxy-3-indoleacetic acid methyl ester are obtained in a white or slightly brown crystalline mass of elongated prisms, melting point 7274, 75 C. the ester being pure enough for the subsequent reactions. By further crystallizing from a little methanol a perfectly white ester, m.p. 74-75 C. is obtained.

Found: C% 70.16 (calc. 70.30); H% 7.09 (7.00); N% 5.13 (5.12). The ester rapidly reduces potassium permanganate in an acetone solution and yields through hydrolysis with 0.5 N alcoholic potassium hydroxide solution the corresponding free acid: melting point l04-l06 C. (crystallized from cyclohexane).

Part 2Preparation of alcoholic solution of hydroxylamine 0.920 g. sodium are dissolved in 15 ml. anhydrous methanol. This solution is admixed with a solution of 1.4 g. hydroxylamine hydrochloride in 15 ml. methanol. The precipitated sodium chloride is promptly filtered off and the volume of the filtered solution is brought to 42 ml. by means of further methanol. The solution may be conserved a few hours only, at low temperature.

Part 3-l-Allyl-2-methyl-5-methoxy-3-indoleacetohydroxamic acid (I/A) CH CONHOH 0.910 g. (one three-hundredth M) of the l-allyl-2-methyl-S- methoxy-3-indoleacetic acid methyl ester are dissolved at elevated temperature in 4 ml. anhydrous methanol and admixed all at a time with 14 ml. of the methanol solution of hydroxylamine (one one-hundred fifthieth M) and refluxed during half an hour.

The methanol is thereupon evaporated in vacuum, the

residue being dissolved in 101 1 ml. water, filtering if necessary. The clear alkaline-reacting solution is neutralized (pH 6 6.5) while cooling with 2N hydrochloric acid. A thick oily product precipitates, which sets either at once or with time, this product being separated by filtering, repeatedly thoroughly washed with a little water and purified by consecutive crystallizations from hot benzene. The result is 0.550 g. I/A in the form ofa white mass oftiny needles (mp. 131-133 135 C. (dec.)). Found: C% 65.38 (calc. 65.60); H% 6.65 (6.65); N% 9.93 (10.21). The product is soluble in alkaline-reacting solutions, but not in bicarbonate; when dissolved in methanol, it turns violet on adding an aqueous solution of a ferric salt.

EXAMPLE 2 Part 21-p-chlorobenzoyl-2-methyl-5-methoxy-3-indoleacetohydroxamic acid (l/C) l-Benzyl-2-methyl-5-methoxy-3-indoleacetohydroxamic acid (VB) 5 011,0 ONHOH cmcomion (111:0

CHa cmo -CH3 i (:0 N

I CH1 Cl (vm A solution of 1.330 g. sodium hydroxide in ml. water is 1080 g (about one threemundredth M) of 2 slowly admixed with 2.330 g. hydroxylamine hydrochloride methyl-5-methoxy-3-indoleacetic acid methyl ester m.p. whiie Cooling, whereupon i ghloride of l:p-chlorobe nzoy l 72-75 C. (prepared similarly as described in example 1, part 2'meihyi5"hethoxy'3'ihdoieacfihc acidlis p i' this 1, in respect of the l-allyl-derivative) are dissolved at elevated heutral or silghdy aikahhe Solution by Vigorousiy Stirring temperature in 4 ml. anhydrous methanol, then refluxed with mg a few i' 8 ml. of a methanol solution of hydroxylamine (example 1, h acid chioiicie reacts with the free hydroxylamine Wiih pan 2 during 5 minutes considerable rapidity apparently without dissolving. The reac- The solution is thereupon acidified with concentrated tion is Completed when a Sample of the suspension shows hydrochloric i up to abou =3 and the solvent is become clear on adding aqueous alkali. The crystalline paleevaporated in vacuum; the residue is finely disintegrated in 20 yeiiow a of i/c P f is sepai'aied y filtering, iavishi) ml. water and the undissolved matter is, separated by filtering, washed with water and dried Vachuih- The Crude Piodhci further washed with water, dried and carefully repeatedly puyield is fy l The Pmcih'iit is Purified with rified from benzene yielding about 0.500 g. of a white mass of ceiieht yields by repeatedly crystallizing from hot dioxane and tiny needles, melting point 145-l49C. (dec.) (I/B). washing with ether; -P- i8 -i Found: c% 69.89 (calc, 70.35 H% 6.21 (6.21); N% 8.56 Found: C% 61-16 H% -6 N 7-41 (8.63). The product is soluble in alkaline-reacting solutions (751 )Ci (9-5i and turns violet on adding a f i Salt. The product is soluble at elevated temperature in many organic solvents, from which it may be recrystallized, but is then EXAMPLE 3 typically obtained in a less pure condition. It gives rise in alcohols to the peculiar reaction of hydroxamic acids with ferric salts; is soluble in strong alkalies in which, however, it is quickly hydrolyzed even at room temperature and forms the Part l-l-p-chlorobenzoyl-2-methyl-5-methoxy-3-in- 40 doleacetic acid chloride G z@ 001 debenzoylated product I/D (dealt with hereinafter). mo 0 EXAMPLE 4 2-Methyl-5-methoxy-indole-3-acetohydroxamic acid (l/D) N (g0 CHzC ONHOH /CH; 1 01 11 H IX l g. of l-p-clorobenzoyl-2-methyl-5-methoxy-3-indoleacetic 2.75 g. one one-hundredth M) of 2-methyl-5-metho'xy-3-inacid (J. Am. Chem. Soc. 85, 488489 (1963)) is treated in a doleacetic acid tert-butyl ester are refluxed with 28 ml. of nitrogen stream with 10 ml. thionyl chloride in which it methanol solution of hydroxylamine (compare example I, promptly dissolves. The solution is quickly evaporated in part 2) during 3 The solution is cooled and filtered, if vacuum and the residue (which typically is of a deep brownslightly opalescent, the solvent being evaporated in vacuum; green color) is distempered, twice or three times, with a few the residue is taken up with water and further alkalized with a ml. anhydrous benzene which is removed in vacuum each little sodium hydroxide. The small amount of insoluble starttime. The resulting residue is thoroughly distempered with 5 ing product which is still unreacted is filtered ofi, and the soluml. anhydrous ether which dissolves most of the color impurition is treated with 2N hydrochloric acid up to about pH=5. ties, and separated by filtering, purified by crystallizing from The resulting precipitate is separated, washed with an aqueous plenty of anhydrous ether, yielding a crystalline mass of neesaturated solution of sodium bicarbonate, then with water and dles of straw-yellow color, m.p. 124l27C. Yield: 0.700 g. dried; purification is effected by crystallizing from dioxane, Found: Cl% 18.62 (calc. 18.84). followed by crystallization from anhydrous alcohol, the result The product is relatively stable towards water and aqueous being 1.75 g. l/D, melting point l72l74 C. (dec.), in a alkalies in which it proves to be insoluble even after dwelling white crystalline mass. therein several hours at room temperature. It reacts, better if Found: C% 61.68 (calc. 61.52); H% 5.89 (6.02); N% l 1.87

at elevated temperature, with lower alcohols with which it (11.96). forms the corresponding esters, and with ammonia under This product may alternatively be obtained, as mentioned suitable conditions for forming the amide (m.p. 219-22l hereinbefore. by alkaline hydrolysis of l/C at room tempera- C.). 75 ture.

For this purpose, 1 g. I/C is dissolved in a solution of 2 ml. sodium hydroxide in ml. water. The originally yellow solution readily tends to become paler and is filtered after a few minutes, acidified with 2N hydrochloric acid till thorough precipitation (pH about 5), admixed with sodium bicarbonate up to about pH-8.3, well stirred, the undissolved product (l/D) being separated by filtering and purified as described above. 7

By a strong acidification of the mother liquor of the hydrolysis reaction p-chloi'obenzoic acid .can be obtained as byproduct of the hydrolysis. 7 Note: The melting points of the compounds obtained in the examples were determined with a Kofler microscope equipped with heating table. The thermometric values have not been corrected.

PHARMACOLOGICAL INVESTIGATIONS The compounds were submitted to the following investigations:

1. Determination of the 50 percent lethal dose (LD on rats. 2. Determination of the inhibiting action towards the experimental edemas from a. carrageenan b. formalin 3. Determination of the inhibiting action towards the granuloma from polyvinylpyrrolidone sponge. 4. Determination of the analgesic action. 5. Determination of the antipyretic action. The acompound employed as control was indomethacin 1-p-chlorobenzoyl-2-methyl-5-methoxy-3l7 -indoly1acetic acid) on account of the chemical structure resemblances to the compounds tested. 1. Determination of the 50 percent lethal dose on rats:

The determination was carried out on albine rats of both sexes of average weight of 200 g'. by oral administration of the compounds suspended in olive oil. The administered volume did not exceed 0.2 m1./ 100 g. The mortality percentage was ascertained 4 days after administration.

The results (which were elaborated by the statistical method of .l. T. Litchfield Jr. et al. Journal of Pharm. Exp. Therap. 96, 99, 1949) are summarized in table 1.

TABLE] LD n mgJkg. per 05 Number of Compound (with confidential limits) animals lndomethacin 23 (16-31 6S l/C 96(72-118) 74 VD 101 (81-128) 62 VA 79 (62-97) 73 m; 81 es-r04 79 2. Determination of the inhibiting action towards experimental edema from:

a. carrageenan The detennination was carried out on albine rats of both sexes of average weight of 150 g. The inflammation was induced by injecting into the subcutaneous tissue of left-hind paw 0.1 ml. of a 0.1 percent sterile physiological solution of carrageenan (Genulacta Karrageenan type Ll 00, Kobenhavns Pektin F abrik, Lille Skensved, -y Denmark The intensity of the induced inflammation was estimated by measuring the volume of the paw by a pletisomometric method (immersion of the limb down to the tibiotarsal articulation into an overflow receptacle and measurement of the displaced liquid quantity). The difference between the limb volume before the injection of carrageenan and 5 hours later stands for the intensity of the edema.

The compounds were administered per os suspended in olive oil, by a volume not exceeding 0.2 ml./l00 g. 1 hour before the carrageenan injection.

(Reference is made for further details of the method to: Ar-

rigoni Martelli E. et al.: I1 Farmaco ed. prat. 19, 134. 1964; Winter C. A. et al., Proc. Soc. exp. Biol. A. Med. 111, 514, 1963).

The results summarized in table 2a express the percentage inhibition of the edema.

All experimental conditions are similar as previously described.

The inflammation was induced by injecting into the subcutaneous tissue of the left hind paw 0.1 ml. of a 1 percent formalin solution.

TABLE 2b inhibition Number of Compound Dose :S.E. animals mgJkg.

lndomethacin 2.5 19.5:L6 35 lndomethacin 5.0 253:2.2 30 lndoinethacin 10.0 39.6:31 35 I/C 2.5 ZLJtLS 30 NC 50 33422.1 35 l/C 10.0 44.5214 35 III) 2.5 l6.5t2.5 35 I) 5.0 27.3236 40 III) 10.0 40214.9 40 HA 2.5 8521.9 30 HA 5.0 I3.6:3.2 30 NA 10.0 19.3218 35 NB 2.5 8.9:L6 35 UK 5.0 [1522.8 35 III! 10.0 [9.5184 35 3. Determination of the inhibiting action towards the granuloma from polyvinylpyrrolidone sponge.

The determination was carried out on albine rats of both sexes of average weight of 200 g. The animal was subjected to a slight anesthesia by ether and a polyvinylpyrrolidone sponge weighing about 20 mg. was introduced under the skin of the interscapular region.

The incision was sutured by a silk stitch. Beginning with the next day and during 8 consecutive days the compounds suspended in olive oil were orally administered by a volume not exceeding 0.2 mI./ g. On the 9th day the animals were sacrificed; the granulomatous tissue formed and the sponge therein contained were carefully dissected from the surrounding tissues and weighed after standing 18 hours at 50 C.

The results are summarized in Table 3 4. Determination of the analgesic action The determination was carried out on albine rats of both sexes of average weight of 150 g. The analgesic effect of the compounds was estimated by measuring the pressure exerted on the left hind paw inflammed by injection of brewers yeast (0.! ml./animal ofa 20 percent solution) which causes painful reactions in the animal.

The procedure is described in detail by L. O. Randall et al.: Arch. in Pharmacodyn. 111,409, 1957.

The compounds were orally administered suspended in olive oil (0.2 ml./l g. 1 hour before inducing the phlogosis.

The results summarized in table 4 express the percentage inhibition ofthe pain sill.

5. Determination of the antipyretic action The determination was carried out on albine rats of both sexes ofaverage weight of 200 g.

The temperature index was determined as represented by the sum of temperature readings effected at 30 min. intervals beginning l'hour after administration of the pyrogen (0.5 mg./kg. by weight of lipopolysaccharide of E.Coli) less 10 times the basal temperature (reference is made for information about the detailed procedure to C. A. Winter et al., Journal Pharm. Exp. Therap. 141, 369, 1963).

The compounds were suspended in olive oil and orally administered hour before the pyrogen.

CONCLUSIONS The tested compounds are of a high anti-inflammatory action, as is evidenced by the results of the tests with two types of acute experimental phlogosis; namely, carrageenan and formalin edemas and one type of chronical phlogosis, namely, the foreign body granuloma. They exert moreover analgesic and antipyretic action.

The tested compounds distinguish by a considerably low acute toxicity, so that the therapeutical index is particularly favorable. The most advantageous compound appears to be the l-p.chlorobenzoyl-Z-methyl-5-methoxy-3-indoleacetohydroxamic acid (l/C).

PHARMACEUTICAL PREPARATION S The derivatives as hereinbefore described are suitable for both oral and rectal administration, as per the following examples.

A.Capsules A gelatine capsule type 2 (Snap-Fit, Parke & Davis) is filled with an intimate mixture of 25 mg. l-p.chlorobenzoyl-2- methyl-5-methoxy-3-indoleacetohydroxamic acid (l/C), 220 mg. lactose, 4 mg. talcum and 1 mg. magnesium stearate. The weight ofthe filled capsule is 0.330 g.

B.Tablets g.

Tablets of 8 mm. diameter are prepared from an intimate mixture of 25 mg. HQ 220 mg. lactose, 4 g. talcum and l g. magnesium stearate per tablet.

C.Suppositories Suppositories weighing 1.600 g. are prepared using 50 mg. I/C per suppository and polyethylene glycol as excipient.

Capsules and tablets as described above are used at a typical dosage of l-2 units three times a day (after meals). For rectal use, 3-4 suppositories daily are indicated.

The excipients indicated hereinbefore are typical for the pharamaceutical preparations according to this invention. It is, however, to be understood that other excipients, inert to the derivative involved, may be found convenient and employed by those skilled in the art.

Warning:The derivatives of this invention are sensitive to heavy metals and heavy metal compounds. Accordingly, in the preparation of both said derivatives and their pharmaceutical forms any contacts with mechanical parts yielding said metals and compounds are preferably to be avoided; also the excipients used shall be free ofsaid metals and compounds (even in traces). As heavy metals are understood herein metals having a density in excess of 5, mainly iron, copper, zinc, lead. tin, bismuth, cadmium, mercury, cobalt, nickel and manganese.

We claim:

1. A 2-methyl-5-methoxy-3-indoleacetohydroxamic acid compound of the formula:

CHzCONHOH 3. The compound ofclaim 1 wherein R is phenyl-methyl. 4. The compound ofclaim 1 wherein R is p-chlorobenzoyl. 5. The compound ofclaim 1 wherein R is hydrogen.

t t t 

2. The compound of claim 1 wherein R is allyl.
 3. The compound of claim 1 wherein R is phenyl-methyl.
 4. The compound of claim 1 wherein R is p-chlorobenzoyl.
 5. The compound of claim 1 wherein R is hydrogen. 